Phytophthora nicotianae引起之觀賞植物疫病新紀錄

Newly recorded diseases of ornamental plants caused by Phytophthora nicotianae in Taiwan

自西元2004年至2015年於田間採集疫病病害標本，共發現與鑑定23種觀賞作物罹患由Phytophthora nicotianae引起的新紀錄疫病。罹患疫病的23種觀賞植物寄主包括：燈籠扶桑、玲瓏扶桑、瑪格莉特菊、愛元果、鳥尾花、金露花、勳章菊、木芙蓉、非洲鳳仙花、垂笛花、長壽花、馬櫻丹、星辰花、紅蟬花、袋鼠花、伯利恆之星、繁星花、藍雪花、桃金孃、天堂鳥、海豚花、夏蓳及美女櫻等，大部分寄主均為近年來新引進的觀花或觀葉植物。這些植物中，以愛元果、木芙蓉、垂笛花、袋鼠花、伯利恆之星、及海豚花發病最為嚴重，全株可被感染，嚴重時，會導致罹病植株死亡。其餘之寄主植物，發病部位包括幼嫩的莖、葉、花及細根部位。為害這23種寄主的疫病菌P. nicotianae，共分離到118菌株（56A1:62A2），均為典型菌株，孢囊單假軸著生，圓形或卵圓形，兩側稍微不對稱，具明顯乳突，不具脫落性；藏卵器表面平滑，藏精器單生單室底著；具厚膜孢子。生長溫度最高可達35-36℃，最適生長溫度為24-28℃。ITS DNA序列與收集在NCBI GenBank資訊庫中疫病菌之的相同度分別高達99.88-100%，屬於Cooke等人分子分類群的第Ｉ類群（clade）。本試驗研究顯示P. nicotianae基因序列的比對結果與形態鑑定結果具一致性。

"From 2004 to 2015, diseased samples caused by Phytophthora were collected from gardens and fields. A total of 23 species of ornamental plants infected with Phytophthora nicotianae were identified and recorded for the first time in Taiwan. These 23 species of ornamental plants infected with Phytophthora consisted of flowerin maple (Abatil on megapo-lamicum) cape mallow (Anisodontea capensis), marguerite (Chrysanthemum frutescens), pillow fight (Dischidia pectenoides), firecracker flower (Crossandra infundibuliformis), golden dewdrop (Duranta repens), treasure flower (Gazania splendens), cottonrose hibiscus (Hibiscus mutabilis), African impatiens (Impatiens walleriana), Brazilian fuchsia (Justicia rizzinii), kalanchoe (Kalanchoe blossfeldiana), lantana (Lantana camara), statice (Limonium sinuatum), Brazilian jasmine (Mandevilla sanderi), goldfish plant (Nematanthua cheerio), giant chincherinchee (Ornithogalum saundersiae), startcluster (Pentas lanceolata), plumbago (Plumbago auriculata), downy Rose myrtle (Rhodomyrtus tomentosa), bird of paradise flower (Strelitzia reginae), false African violet (Streptocarpus saxorum), torenia (Torenia fournieri), and garden verbena (Verbena hybrida). Among these plants, sever disease symptoms were observed on Dischidia pectenoides, Hibiscus mutabilis, Justicia rizzinii, Nematanthua cheerio, Ornithogalum saundersiae, and Streptocarpus saxorum. A total of 118 isolates (56A1:62A2) of the Phytophthora isolates infecting these ornamental plants were obtained. All of them showed typical morphological characteristics of P. nicotianae. Sporangia were produced simple sympodiumly on sporangiophores, round to ovoid, slightly asymmetrical on both sides, papillate prominently, and nondeciduous. Oogonial walls were smooth and antheridia were amphigynous. Chlamydospores were also observed. Maximum temperature for mycelial growth was 3536℃, with optimum temperature at 24-28℃. The ITS sequences of these isolates were up to 99.88-100 % identity with sequences of P. nicotianae collected in NCBI GenBank database, and thus can be classified as Phytophthora clade I. Blasting results of these P. nicotianae isolates were consistent with classification based on morphological characters."